The objective of the proposed program of research is to study the targeting of phospholipid vesicles in vivo in mice using perturbed angular correlation spectroscopy, and vesicles modified with synthetic glycolipids and other cell surface receptor analogues. Preliminary studies of the targeting of phopholipid vesicles in vivo have indicated that the perturbed angular correlation technique provides a unique capability for studying the integrity of substituted phopholipid vesicles in vivo in mice. It is proposed to exploit this unique capability by exploring in greater detail the mechanism by which aminomannose-labeled vesicles are recognized and transported in vivo, and by examining a wider variety of cell surface receptor analogues.